Actually, if you started working with Linux back when Slackware was cutting edge, you'd consider today's Ubuntu to be a dream to work with. That and the package you are trying to install is a debian package.... supported by Ubuntu but not Ubunbtu software.
If stability and relatively error free operation is your goal, you should not be installing or upgrading pre-released updates. Pre-release is, by definition not thoroughly tested and could very well have bugs. Some serious.
Off the top it looks like the package you are trying to install is corrupted so the error message you are seeing is the system protecting itself from installing a "bad" package.
If this is a package that you really need and want, a first step after downloading it would be to run a checksum against it to make sure that it is a legit package and that the file is not corrupted. There are lots of threads here that explain in depth how to do this.
If you don't actually need this package and especially if this package is a pre-release, you are probably better off NOT trying to install it.